From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
	id 5C4DD3858404; Tue, 11 Jul 2023 15:36:46 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 5C4DD3858404
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1689089806;
	bh=k1A70MBublPJMPEtBdUBfNubV08AS5TOejKlbucSbts=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=o6aAARHLc5kJovgvG0cKrhP1yVYERLyLS2VE/5zcF9W/m1/OD4rk71PWuHBd+Q/9J
	 pkL7eHhXfCr8gzuaJphoImvJjsQkToN1JwyfxK/jNSZz4DMlNY8+cyL48VrXSkQNUc
	 DKiZgaNvmALVKGYNL/tlzz+Gs61mTMUN7whrLjc8=
From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/106884] ifcombine may move shift so it shifts
 more than bitwidth
Date: Tue, 11 Jul 2023 15:36:45 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 13.0
X-Bugzilla-Keywords: wrong-code
X-Bugzilla-Severity: normal
X-Bugzilla-Who: pinskia at gcc dot gnu.org
X-Bugzilla-Status: NEW
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-106884-4-7rPGNM5lC5@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-106884-4@http.gcc.gnu.org/bugzilla/>
References: <bug-106884-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
List-Id: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106884

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #4)
> But yes, since we now unconditionally compute 1<<b after the transform
> GCC could assume b is in range.  We are lacking a way to compute 1<<b
> optimally without that undefined behavior.

phiopt will almost definitely run into a similar thing though right now, it=
 has
not.=